U.S. EPAs Models for Establishing Cleanup Levels in Soil, Water, - - PowerPoint PPT Presentation

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U.S. EPA’s Models for Establishing Cleanup Levels in Soil, Water, Buildings and Streets at Superfund Sites

Stuart Walker U.S. Environmental Protection Agency Office of Superfund Remediation and Technology Innovation (OSRTI) Science and Policy Branch Presented to the IAEA EMRAS II Workgroup "NORM & Legacy Sites" in Vienna, Austria on September 23, 2009

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Purpose

• 1. Provide brief overview of EPA Superfund

approach for selecting cleanup levels and use

• f risk/dose assessment
• 2. Provide overview on new and upcoming

CERCLA risk assessment calculators, guidance, and training for Radionuclides

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Part 1 EPA Superfund Approach for Selecting Cleanup Levels

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EPA Addresses Site Cleanup Under Several Law s, Programs

Comprehensive Environmental Response, Compensation & Liability Act, CERCLA or “Superfund” National Contingency Plan (NCP) is regulation for CERCLA National Priorities List (NPL) guides EPA on which sites need further attention

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What does a Superfund Site look like?

There are many different types of Superfund sites. »See following 4 pages for examples of radioactively contaminated sites.

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Nuclear Metals Inc. - Massachusetts

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Abandoned Uranium Mines Project – Navajo Nation

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Welsbach/General Gas Mantle – New Jersey

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Hanford – D Reactor / DR Reactor Remediation

Contaminated Soil Remediation Effluent Piping Removal D Reactor Surveillance and Maintenance DR Reactor Interim Safe Storage Project

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CERCLA Decision-making

CERCLA cleanup decisions are made site- specifically » Must comply with CERCLA and NCP EPA Regional site managers » Removals – On Scene Coordinators (OSCs) » Remedial (and NTC-removals) – Remedial Project Managers (RPMs)

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Nine CERCLA Remedy Selection Criteria

Two threshold criteria (both must be met)

• 1. Protect human health and the environment
• 2. Comply (attain or waive) with other federal

and state laws: Applicable or Relevant and Appropriate Requirements (ARARs) — Protect current or future sources of drinking water (e.g., attain MCLs or more stringent state standards)

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Nine CERCLA Remedy Selection Criteria (continued)

6 CERCLA ARAR waivers

• 1. Interim Measure
• 2. Greater Risk to Health and the Environment
• 3. Technical Impracticability
• 4. Equivalent Standard of Performance
• 5. Inconsistent Application of State

Requirements

• 6. Fund Balancing

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Nine CERCLA Remedy Selection Criteria (continued)

Five balancing criteria (used to evaluate between potential remedies that meet threshold criteria)

• 1. Long-term effectiveness and permanence
• 2. Reduction of waste toxicity, mobility, or

volume

• 3. Short-term effectiveness
• 4. Implementability
• 5. Cost

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Nine CERCLA Remedy Selection Criteria (continued)

Two modifying criteria (information from public comment period that may modify remedial action)

• 1. State acceptance
• 2. Community acceptance

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CERCLA Cleanup Levels

ARARs often determine cleanup levels Where ARARs are not available or protective, EPA sets site-specific cleanup levels that » For carcinogens, represent an increased cancer risk of 1 x 10-6 to 1 x 10-4

—10-6 used as “point of departure” —PRGs are established at 1 x 10-6

» For non-carcinogens, will not result in adverse effects to human health (hazard index (HI) <1) Address ecological concerns To-be-considered (TBC) material may help determine cleanup level

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CERCLA Cleanup Levels Are NOT NOT Based On

NRC decommissioning requirements (e.g., 25, 100 mrem/yr dose limits) 10 CFR 20 Subpart E » If used as an ARAR, 10-6 still used as point of departure, and 10-4 to 10-6 risk range must be met Guidance outside risk range and/or if expressed as a dose (# mrem/year). This includes: » DOE orders, NRC guidance (e.g., NUREGs), ICRP guidance, IAEA guidance, NCRP guidance, ANSI/HPS guidance, EPA/DHS PAGs, and Federal guidance

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Risk-based Cleanup Levels for Radioactive Contamination

Radiation cleanup levels expressed as risk levels, not mrem [mSv] Superfund uses “slope factors” in Health Effects Assessment Summary Tables (HEAST) instead

• f dose conversation tables to estimate cancer

risk from radioactive contaminants » HEAST has been updated with new information from Federal Guidance 13 —Based on information in ICRP 72

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EPA/ITRC CERCLA Policy and Guidance Training

Four modules provide:

• 1. Radiation Regulatory Background and Case

Studies

• 2. Overview of CERCLA Requirements
• 3. EPA CERCLA Radiation Guidance and

Tools

• 4. Challenges of Long-Term Management of

Radiation Sites

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EPA/ITRC CERCLA Policy and Guidance Training, cont.

Five Live Internet rad CERCLA Policy Training sessions have been conducted » 838 total participants, including 163 EPA employees An archived version of a live training session is available at: » http://www.clu-in.org/conf/itrc/radscleanup_060507/ Archived version was accessed by users 3,282 times between January 1, 2008 and August 26, 2009.

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Radiation Human Health Assessment Approaches

RISK APPROACH » Where risk is calculated directly by assigning a unit

• f risk for every unit of exposure (Cancer Slope

Factor) and multiplying by the total exposure. DOSE APPROACH » Where dose is calculated by multiplying a dose conversion factor by the total intake/exposure. » The calculated dose can also be multiplied by a probability coefficient to arrive at a risk value.

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Radiation Human Health Assessment Approaches Risk = Exposure X Cancer Slope Factor Dose = Exposure X Dose Conversion Factor (DCF)

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Inhalation Pathw ay Example:

RISK = (Inhalation Slope Factor) X (radionuclide concentration in air) X (breathing rate) X (exposure duration) DOSE = (DCF) X (radionuclide concentration in air) X (breathing rate) X (exposure duration)

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Standards expressed in terms of dose equivalent (e.g., NRC’s 25 mrem/year) Standards expressed in terms of risk (e.g., EPA’s 10-4-10-6 CERCLA risk range) Dose equivalent is measured in units of rem, mrem, or sievert Risk is a unitless measurement

• f the likelihood of an adverse

affect DCFs based on populations from

• ther nations

Slope factors based primarily on US population Annual exposure to an average member of the “critical group” (NRC) Lifetime exposure to an individual with a reasonable maximum exposure (EPA)

DOSE RISK Basis for Risk and Dose Approaches

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Basis for Risk and Dose Approaches, cont.

Does not consider other competing causes of death Considers causes of death other than radiation-induced cancer Dose equivalent includes both low-LET and high-LET radiation multiplied by appropriate Relative Biological Effectiveness (RBE) factors Low-LET & high-LET estimates considered separately for each target organ DCFs consider genetic risk Slope Factor does not consider genetic risk Age-dependent (separate DCFs, for infants, children, and adults) Age- and sex-dependent risk models in Slope Factors

DOSE RISK

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Basis for Risk and Dose Approaches (cont.)

RBE for alpha radiation = 20 for all sites RBE for most sites = 20; RBE for breast =10; for leukemia =1 Fixed length of 50 years for integration period Variable length to integration period (< 110 years) Lung dose based on average dose to tracheobronchial, nasopharyngeal and pulmonary regions Lung dose based on absorbed dose to tracheobronchial and pulmonary regions Effective dose considers dose estimates to 12+ target organs (+ average of 10 other organs) Estimates of absorbed dose to 16 target organs/tissues

DOSE RISK

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Radiation Human Health Assessment Approaches

Dose values may be converted into risk and vice versa using conversion factors Dose and Risk are closely related » [Risk = (total dose) X (probability coefficient in risk/unit dose)] Risks converted from dose may vary as much as 10 times from risks based on slope factors for some types of exposure

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Part 2 New and Upcoming Superfund Radiation Risk Calculators and Training

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Guidance: Risk Assessment Q& A

Radiation Risk Assessment at CERCLA Sites: Q&A (12/99) OSWER Directive 9200.4-31P Provides overview of current EPA guidance for radiation risk assessment Written for users familiar with Superfund but not radiation Adds some new guidance

» Dose assessment only for ARAR compliance » No dose-based TBCs (including No 15 mrem/yr [0.15 mSv/yr] for selecting cleanup levels) » Direct exposure rate may supplement sampling

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Guidance: Rad SSG

Soil Screening Guidance for Radionuclides [rad SSG] documents (10/00) OSWER Directives 9355.4-16A and 9355.4-16

» User Guide » Technical Background Document

Guidance to screen out areas, pathways, and/or radionuclides early in the process Consistent with 1996 chemical SSG

» 1 x 10-6 and MCLs (leaching from soil) » Residential land use » Survey procedures for site characterization » Evaluates 5 soil to groundwater models » Accounts for technical differences of radiation

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CERCLA Risk and Dose Calculators (final and draft)

Human Health

Cancer risk (1 x 10-6) PRG (soil and water) BPRG (inside buildings) SPRG (outside surfaces)

Ecological

REB (aquatic, riparian, terresterial, plants and animals Dose (millirem per year) DCC (soil and water) BDCC (inside buildings SDCC (outside surfaces)

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Default Parameters

All CERCLA risk and dose assessment calculators for radionuclides allow default runs » Default parameters already established » Just select a scenario and radionuclides and click on retrieve

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Site-Specific Paramters

All CERCLA risk and dose assessment calculators for radionuclides allow site-specific runs » Change default parameters with defensible site-specific or regional information » Still select a scenario and radionuclides, but then see each parameter

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EPA CERCLA Policy on Changing Defaults

Site managers should weigh the cost of collecting data with the potential for deriving significantly different concentrations (either PRG

• r DCC)

» Defaults are generally conservative » Using site-specific data will usually result in higher allowable concentrations for same risk

• r dose estimate

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How NOT to Change Defaults

In general, should not replace default parameters with literature values »Including defaults from other Agencies or other EPA programs »Should be same values for parameters used with chemicals for the same receptor at the same site

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Guidance: Rad PRG Calculator

Calculator to establish PRGs, when: » ARAR is either not available or sufficiently protective (e.g., 25 mrem/yr [0.25 mSv/yr]

• r more)

Electronic equations (risk and leaching to groundwater) also are on Internet » 1x10-6 and MCLs (leaching from soil) » Accounts for technical differences of radiation (e.g., gamma, plant uptake)

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Guidance: Rad PRG Calculator (continued)

Seven scenarios/land uses available Chemical SSL Internet equations should be used for chemical toxicity of uranium

• 1. Residential
• 2. Agricultural
• 3. Indoor workers
• 4. Outdoor workers
• 5. Fish ingestion
• 6. Tap water
• 7. Soil to groundwater

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Guidance: ARAR Dose Calculator

Calculator to establish Dose Compliance Concentrations (DCC) for single dose limit ARARs requiring a dose assessment Six scenarios/land uses available Equations similar to those used for PRG calculator, except dose conversion factors used instead of slope factors

• 1. Residential
• 2. Agricultural
• 3. Indoor workers
• 4. Outdoor workers
• 5. Fish ingestion
• 6. Tap water

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EPA/ITRC Radiation Risk Training

Four modules provide:

• 1. Background and Regulatory Case Studies
• 2. Existing Practices in Radiation Risk

Assessment

• 3. Use of Radiation PRG Calculator (tutorial
• n using PRG and ARAR dose calculator)
• 4. Case Study Application for PRG

Calculator

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EPA/ITRC Radiation Risk Training, cont.

Eight Live Internet rad CERCLA Policy Training sessions have been conducted » 1,047 total participants, including 165 EPA employees An archived version of a live training session is available at: » http://www.clu-in.org/conf/itrc/rads_051507/ Archived version was accessed by users 1,710 times between January 1, 2008 and August 26, 2009.

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Guidance: Building PRG (BPRG) Calculator

Calculator to establish 1x10-6 risk based PRGs for the reuse of radioactively contaminated buildings. Equations and parameters are derived from latest EPA chemical methodology (e.g., assessment at WTC) » Adjusted to account for technical differences posed by radiation

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Guidance: Building PRG (BPRG) Calculator (continued)

BPRG calculator includes 2 land use scenarios »Residential »Indoor worker Both land uses include 3 exposure routes »Settled dust »Ambient air »Direct external exposure —5 Room sizes and 4 receptor locations, both –Surface –Volumetric

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Building Dose Cleanup Concentrations (BDCC) ARAR Dose Calculator DRAFT BDCC Purpose: to establish BCCs for Inside Buildings for single dose limit ARARs (# mrem/yr) BDCC includes 2 land use scenarios (Residential, Indoor Worker) 2 land uses include 3 exposure routes (Settled dust, Fixed Direct External 3-D, Ambient Air) Equations similar to those used for BPRG calculator, except dose conversion factors used instead of slope factors

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Surfaces PRG (SPRG) Calculator

Establish 1 x 10-6 risk based PRGs for radioactively contaminated outside hard surfaces (e.g., slabs, pavement, sidewalks, sides of buildings) Derived from rad PRG and BPRG calculators

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SPRG Exposure Scenarios

SPRG includes 3 land use scenarios » Residential » Indoor Worker » Outdoor Worker 3 land uses include 3 exposure routes » Settled dust (pave and unpaved street level) » Fixed Direct External 3-D (street level) —Surface and Volumetric » Fixed Direct External 2-D (slabs) —Surface and Volumetric

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Surface Dose Cleanup Concentrations (SDCC) ARAR Dose Calculator DRAFT SDCC Purpose: to establish DCCs for Outside Hard Surfaces for single dose limit ARARs (# mrem/yr) SDCC includes 3 land use scenarios (Residential, Indoor Worker, Outdoor Worker) 3 land uses include 3 exposure routes (Settled dust, Fixed Direct External 3-D, Fixed Direct External 2-D (slabs)) Equations similar to those used for SPRG calculator, except dose conversion factors used instead of slope factors

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EPA/ITRC Radiation D& D Training

Four modules provide:

• 1. Introduction and Regulatory Basis for D&D
• 2. Factors for Implementing D&D
• 3. Preliminary Remediation Goal (PRG)

Calculators (tutorial on using BPRG, SPRG, BDCC, and SDCC calculators)

• 4. Case Studies and Lessons Learned

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Radiation D& D Training, cont.

Five Live Internet rad CERCLA Policy Training sessions have been conducted » 731 total participants, including 101 EPA employees An archived version of a live training session is available at: » http://www.clu-in.org/conf/itrc/radsdd_040308/ Archived version was accessed by users 2,046 times between January 1, 2008 and August 26, 2009.

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Radionuclide Ecological Benchmark (REB) Calculator DRAFT

Establish risk-based Biota Concentration guides (BCGs), or ecological benchmarks, for radioactively contaminated sites Derived from DOE Graded Approach guidance » Includes same dose levels for tissue death » Strong recommendation to look at chemical eco effects

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REB Exposure Scenarios

Includes 12 animal or plant benchmark scenarios »6 generic composite only »6 species-specific/site-specific

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Video: Radiation Risk Assessment

Superfund Radiation Risk Assessment and How you can Help, an Overview (3/05) OSWER Directive 9200.4-37 Video for the general public. It contains information on: » The Superfund risk assessment process when addressing radioactive contamination » How the public is involved site-specifically

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For More Copies or Information

Guidance documents are on Superfund Radiation Webpage:

» http://www.epa.gov/superfund/health/contaminants/radiation/index.htm

Guidance documents for Superfund Radiation Risk Assessment

» http://www.epa.gov/superfund/health/contaminants/radiation/radrisk.htm

For further information or questions, Stuart Walker » Phone: (703) 603-8748 » Fax: (703) 603-9133 » Email: Walker.Stuart@epa.gov

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